Hierarchy definition is important for many electronic products requiring coordination among a plurality of devices. Designation of a particular device or terminal as a controller allows ready synchronization of passwords, for example, in networks employing password security by assuring that all of the plurality of devices employ a common password distributed from a common source such as the controller. An example of such a system is described, for example, in "Encryption System Key Distribution Method and Apparatus", U.S. Pat. No. 4,578,531, by J. Everhard and J Osborn; in "Key Management System" U.S. Pat. No. 5,093,860, by K. Stienbrenner and M. Bright; in "Transaction System Comprising One Or More Host Exchanges And A Number of Distributed Terminal Stations", U.S. Pat. No. 4,962,531, by W. Sipman and L. Snel; or in "Hierarchical Key Management System", U.S. Pat. No. 4,888,801, by R Foster, R. Pfeifer and T. Mihm, which patents are hereby incorporated by reference.
"Voting" systems are used in high reliability applications wherein a plurality of computing devices, for example, each independently perform similar operations on nominally identical data, as described, for example, in "The Architectural Elements of a Symmetric Fault-Tolerant Multiprocessor" by A. Hopkins, Jr . and T. Smith III (IEEE Trans. Comp., Vol C-24, No. 5, pp. 498 through 505) which is hereby incorporated by reference. Such systems suffer from lack of techniques for determining control when N-1 of N many computing devices are faulty. As well, no capability for changing a password, for example, is provided in such a system.
It has been especially uneconomical and impractical to provide for changes in hierarchy in secure communications networks . Typically, such a network may have N many communications units coupled to one another wherein one of the N is the network controller (e.g., authorized key distribution center or key certification authority). In the event that the network controller malfunctions, communications stop and are resumed only when the defect in the network controller has been cleared. This type of network control method provides effective security by cannot gracefully accommodate need to alter the identity of the controlling element, which need may be engendered by disruption of communications or by failure of the controlling element in the network.
Thus, what is needed are a practical and economical method for determining and/or changing an hierarchy and an apparatus for implementing the method, particularly in an environment where the number of elements may change with time and especially in secure communications networks.